Improvement in high-and-low-water indicators for steam-boilers



F. MILLWARD.

Improvement in High and Low Water Indicatbrs fqr Steam-Boilers. N0. "5,501. Patented May 30,1871.

will I H lllllltt mtg -a NIT STATES PATE rrron.

FRANK MILLWARD, or oINcINNATI, oHIo,

' IMPROVEMENT INfHIGH-A ND LOW-WATER INDICAT ORS FOR STEAM-BOILERS.

Specification forming part of Letters Patent No. 115,501, dated May 30, 1871.

I, FRANK MILLWARD, of cinemas, in the county of Hamilton and State of Ohio, have invented a certain newand useful High-or- Low-Water Indicator for Steam-Boilers, of WhlCh thefollowing isaspecification:

Natare and Objects of the Invention.

All low-water indicators for steam-boilers hitherto used have proved unreliable for con- I tinued service. I Indicators whose alarm-vent is governed by a float either inside or outside I of the boiler fail, owing to the water from the the use of joints,which, upon slight corrosion or incrustation, stick and prevent an alarm. Indicators which operate by a slight expan- I sion and contraction of metals require a deli- I cateeasily-displaced adjustment, which has been proved wholly unreliable even for a I short period of time, the parts of the instrument, moreover, being liable to be so clogged with dlItQfI'Olll the boiler in the operation of giving an alarm that'a repetition of it at the I next. occurrence of-low wa ter is impossible.

Indicators which depend for an alarm upon the fusing of a soft-metal plug haveI failed in numerous instances,owingI to the collection of I foreign substances over the face of the plug,

I andowing to the-fusible character of the plug changingwith use. p I I Myinvention, which embodiesa new principle tbr low and-high-water indicators, is designed .to obviate all difiiculties heretofore experienced in the reliable indication of low and high water inIsteam -boilers, and provides an indicator which operates with certaintyand precision under all conditions of boiler pressure,isfree from incrustation, and

stick. I I. p I

' My invention consists of acase or shell composed of two chambers divided by an elastic diaphragm or equivalent, communicating with the water-line and steam-space of the boiler separately, both compartments of the case being under pressure, and one provided with an alarm-valve vent whose valve is operated I has no rubbing or moving parts liable to in one direction by the preponderance of pressure upon one side of the. diaphragm due to the support of a hydrostatic column upon the other side, and in the opposite direction by the retraction of the elastic diaphragm or other retractile force, upon the restoration of equal pressure, after the loss of the hydrostatic column occasioned by the .fall of water in the boiler below the end of the pipe communicating with one compartment of the indicator. I 7

Description of the Accompany ing Drawing.

' Figure 1 is a vertical section of my indicator attached to a boiler for indicating low water, the moving parts of the instrument being in position occupied when the water in the boiler is sufficiently high. Fig. Z isa view of the same instrument when the moving parts have changed position to give an alarm, owing to the absence of suflicient water in the boiler. Fig. 3 is a vertical section of my indicator with theparts arranged for indicating high water, as seen when the water is below high -water mark. Fig. 4 is a view of the instrument shown in Fig. 3 in the act of giving an alarm occasioned by the presence of too much water in the boiler; Figs. 5 and 6 are modifications in the construction of the instrument.

General Description.

A is a metallic case divided into two compartments by a diaphragm, B, the chamber or compartment 0 beingdesigned for the occupancy of steam exclusively, and communicating with the steam-space in the boiler by passage D. The chamber or compartment E is designed for the occupancy alternatelyof water and steam, it being connected to the boiler by pipe F, which ends at the low water mark in Figs. 1 and 2, and at highwater mark in Figs. 3 and 4; The.diaphragm B is constructed to move easily with a slight preponderance of pressure upon one side, and has a valve, G, attached to, forming a part of,

or resting by weight upon it, which seats steam-tight against the valve-seat H.

The seat, valve, and diaphragm may be plated with nickel or other material to prevent corrosion. I

No part of the valve or stem need touch the sides of the aperture for the steam-vent, so that closelyrubbing surfaces liable to stick upon slight corrosion can be avoided entire] T3 permit of the pas age of steam to give the alarm, (see Fig. 2.) the stem of the valve may be much smaller than the hole in the seat, or squared, as shown, or grooved. It should in all cases fit loosely.

The chamber 0 has no communication with the water-space in the boiler; consequently incrustation of the valve and seat, which is of such frequent occurrence in some of the best indicators used heretofore, is impossible in my instrument.

Friction being entirely avoided and incrustation of valve and seat rendered impossible, full confidence can be placed in this instrument for prompt indications in long-continued service.

The valve is as certain of action as a nickelseated safety-valve, and the diaphragm as reliable as that of a steam-gage.

Operation.

When the instrument, in the form used to indicate low water, as shown in Figs. 1 and 2, is attached to the. boiler, the steam has a direct and uninterrupted communication with chamber 0 through passage D. The chamber E (when the water is high enough to cover the end of the tube) is filled with water, and when in this condition the pressure upon the lower side of the diaphragm B is less than that upon the upper side, owing to the presence of the hydrostatic column in pipe F, the downward pressure of which reduces to an extent in direct proportion to its height the upward pressure caused by the steam in the boiler. If the vertical distance from the waterline to the diaphragm is but a little over two feet, a preponderance of one pound per square inch-will exist on the valve side of the diaphragm, which, when the diaphragm is five inches in diameter inside, will give (after allowing a deduction for the unbalanced boiler pressure upon the valve) over eighteen pounds to force and keep the valve to its seat. In order to produce a greater-difference than this it will be only necessary to increase the height of the hydrostatic column. When the water in the boiler has been reduced to a point below pipe F, the water in chamber E is discharged and steam takes its place. The diaphragm is then in equilibrium, except for an area of boiler pressure upon the lower side equal to the areaof the valve-seat, and it then, by retraction to its normal position, and with the assistance of the slight unbalanced boiler pressure upon the lower side, assumes the position shown in Fig.2, opens the valve G, and gives the alarm.

A whistle, I, may be attached to the case A, as shown. The diaphragm itself may form the valve, as shown in Fig. 6.

The form of instrument shown in Figs. 8 and 4 is constructed to indicate high water, and it difiers from that shown in Figs. 1 and 3 in this only--the valve seats on the inside of the case, and is shut when the diaphragm is exposed to a boiler pressure of steam upon both sides. It is forcibly opened by a deflection of the diaphragm when there is an unbalanced pressure due to the presence in tube F of a hydrostatic column.

It is obvious that the details of construction of this instrument may be varied without departing from the principles of construction and operation of the same; as, for example, a piston sliding in a cylinder may be used as the dividing-diaphragm, operated in one direction by a spring or weight, and in the other by the preponderance of pressure opposed to the hydrostatic-column side of the piston, as shown in Fig. 5. The steam may also be conducted to the valve-chamber Gin many ways. The instrument may also be attached in place of one of the boiler gage-cocks, and also combine within itself a gage-cock similar to the old combination of gage-cocks and other indicators.

The diaphragm B may be corrugated concentrically and radially to induce freedom of action, and should be placed so as to discharge any condensed water on-its face back again into the boiler.

In cases where the boiler to which the indicator is to be attached snperheats its steam, it is necessary in most instances that the pipe F should not be surrounded by a steam-jacket, such, for instance, as is shown in Fig. 1. The attachment of pipe F should then be made to the side of the boiler, and may be in place of one of the gage-cocks, the steam being conducted to the chamber 0 by a small separate pipe from the top of the boiler.

In order that air may be expelled from chamber E, when necessary or desirable, to insure the speedy closing of the valve when the boiler is being first fired up, a cock may be inserted near the top of chamber E.

Claim.

Ahigh or-low-water indicator for steam-boilers having two chambers, O E, communicating with the water-line and steam-space of the boiler separately, and a diaphragm alarmvalve, B G, dividing the chambers, operated in one direction by a preponderance of pressure in one compartment created by the support of a hydrostatic columnin the other, and in the opposite direction by any suitable retractile force, substantially in the manner and for the purpose set forth.

In testimony of which invention I hereunto set my hand.

FRANK MILLlVARD.

Witnesses:

ELITHA F. LAYMAN, HENRY MILLWARD. 

